ROANOKE — Attorneys tried to convince a federal judge yesterday that triple killer Percy L. Walton is mentally retarded and suffering from schizophrenia in a last-ditch effort to spare him from execution in the state’s electric chair.

“It’s abundantly clear he doesn’t understand his execution is imminent,” Jennifer L. Givens said of Walton, 24. Miss Givens is asking Chief U.S. District Judge Samuel G. Wilson to grant an evidentiary hearing to explore Walton’s mental competency before the government proceeds with his electrocution — an execution method Walton picked over lethal injection.

The U.S. Supreme Court ruled last year that executing mentally retarded people is unconstitutionally cruel.

Walton’s mental state has become a matter of debate since he pleaded guilty six years ago in state court to three counts of capital murder in a series of slayings in Danville.

Testing by Walton’s own experts did not find him to be retarded, the Virginia Attorney General’s Office said. But an April 30 evaluation by the Department of Corrections determined that Walton appears to be severely mentally retarded.

Another test in May found him to be schizophrenic and psychotic with an IQ of 66. Scoring below 70 on IQ tests generally is considered an indication of mental retardation.

In court yesterday, Robert Q. Harris with the Virginia Attorney General’s Office said intelligence scores taken when Walton was 17 and 18 place him above the accepted mental retardation range, and that recent tests mean little in terms of Walton’s eligibility for execution since the state defines mental retardation as a lifelong condition, measured at the onset of adulthood.

“We can look at his school records. … What we have is an absence of anyone saying he was mentally retarded,” Mr. Harris said.

Walton was three days from execution May 28 when Judge Wilson issued a stay. Defense attorneys argued in court that Walton had a history of mental troubles, suffering from multiple head injuries at an early age, and failing the first and fourth grades in school.

But Miss Givens could not provide any evidence that Walton was mentally retarded before the age of 18.

“What you’re asking me to do is go back and reconstruct what his intelligence was based on testing from a later date,” Judge Wilson said.

After the hearing, a niece of two of Walton’s victims said she thought he was acting dumb to escape his death sentence.

The Kendricks, a couple in their 80s, were found dead inside their town house. Each had been shot once in the top of the head. Two days later, police found the body of Archie Moore, 33, inside a closet in his apartment. Walton had poured cologne on the body and tried to hide it.

Judge Wilson said he would decide soon whether to hold another hearing. If one is denied, Mr. Harris said, Walton will be cleared for execution, and he will have another opportunity to choose between electrocution and lethal injection.